As aircraft systems continue to develop more focus is on reducing both emissions and fuel consumption, in conjunction with the goal of reducing operational and capital costs. These goals may be achieved by increasing efficiencies of systems and/or optimizing systems for a given mission. The disclosed subject matter addresses these needs with a system that allows optimization of accessory power unit sizing, operation and energy recovery in conjunction with low cost power augmentation in the form of onboard high pressure air.
Typically, prior art aircraft employ one or more primary power systems responsible for propulsion, the primary power systems also power subsystems or accessory devices, such as the electrical, hydraulic, environmental, navigation and control systems. Prior art aircraft also include an auxiliary power unit (APU) for supplying power to the accessory systems when the primary power systems are not available. The APU's are used when the aircraft is on the ground or when the aircraft is operating at lower speeds or altitudes, at cruise the primary power systems provide all the power required by accessory systems and the APU is dead weight.
Generation of power for accessory systems by the primary power systems are also complicated by the variable speeds which the primary power systems operate over the course of a mission. This variation requires additional power conditioning equipment to ensure usable electrical power to the accessory systems, which increases both capital and operational costs. In aircrafts, every pound in equipment is a pound lost in payload, which corresponds to lost performance or profit.